Physics Optical Measurement of Magnetic Anisotropy in Thin Garnet Films

Abstract. This paper describes an improved optical method for measuring locally the cubic and uniaxial magnetic anisotropy fields in thin garnet films. The derivative of the in-plane component ofthe magnetization is measured, using a double modulation technique which combines polarization modulation with field modulation. A simple graphical method is devised to calculate Hk and H, from the extrema in this derivative curve. The results of measurements on magnetic garnet films obtained by different methods are compared. Local measurements of the anisotropy induced by substrate facet strain are described. Index Headings: Magnetic anisotropy- Garnet films Several methods have been proposed recently for measuring the magnetic anisotropy of thin garnet films. All of these measurements arebased on either the direct observation of domain configurations [1, 2] or on a measurement of the Faraday rotation under certain external field conditions [3-7]. It is the latter method which we wish to discuss in this paper